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UBC Theses and Dissertations

Particle transport in microfluidic environments : particle adsorption at the polydimethylsiloxane-water interface and the effects of flow field and image processing on the measurement depth in micro particle image velocimetry Mustin, Benjamin

Abstract

This thesis investigates several research questions associated with the transport of microscopic particles in microfluidic environments. This includes an investigation of the motion and deposition of micron sized polystyrene particles at the planar polydimethylsiloxane–water interface. Particle tracking shows that particles near the substrate can be immobilized to different degrees. Careful analysis of the more weakly immobilized particles reveals that there is a buildup of a particle accumulation layer near the substrate in which particle motion parallel to the substrate is hindered by non-hydrodynamic effects. The presence of lateral surface interaction forces resulting from charge heterogeneity of the PDMS substrate is found to be the most plausible explanation for the hindered particle transport across the substrate. The two other problems are concerned with micro particle image velocimetry (μPIV), which is a particle transport-based optical method for the characterization of flow fields in microfluidic devices. One limitation μPIV is the finite measurement depth associated with the optical setup, which can lead to bias errors in the measured flow-velocity. Analytical and numerical models are developed that describe the effect of common image pre-processing filters on the measurement depth in μPIV. Further, previous models are revisited that describe the effect of flow velocity gradients on the measurement depth in μPIV. Supplementary video material is available at: http://hdl.handle.net/2429/54802

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Attribution-NonCommercial-NoDerivs 2.5 Canada